Omega-3 fatty acid
Say it: oh-MAY-guh THREE FAT-ee AS-id
An omega-3 fatty acid is a polyunsaturated fatty acid whose first double bond is three carbons from the methyl end of its chain, as in ALA, EPA and DHA.
Also: omega-3 fatty acids, omega-3s, n-3 fatty acid, omega-3 fat
Definition
What is an omega-3 fatty acid?
Omega-3 fatty acids are polyunsaturated fatty acids, meaning their carbon chains contain more than one double bond. The name refers to where the first double bond sits when the carbons are counted from the methyl end of the chain, which chemists call the omega end: in omega-3s it lies between the third and fourth carbons. The three that matter most in nutrition are alpha-linolenic acid (ALA), with 18 carbons, and two longer ones, eicosapentaenoic acid (EPA), with 20 carbons, and docosahexaenoic acid (DHA), with 22.
Humans cannot make a double bond at the omega-3 position, so ALA is an essential fatty acid that must come from the diet, mainly from plant oils such as flaxseed, canola and soybean oil, and from walnuts and chia seeds. The body can lengthen ALA into EPA and DHA, but only in small amounts, so the main direct sources of these are oily fish, other seafood and algae. DHA is concentrated in the cell membranes of the brain and retina, and EPA is a starting material for signaling molecules called eicosanoids, which help regulate inflammation, blood clotting and blood vessel tone.
Eating seafood is linked to better heart health, and high doses of omega-3s lower blood triglycerides, but trials of supplements for preventing heart disease have given mixed results.
Word parts
Where does the term “omega-3 fatty acid” come from?
- omega
- last letter of the Greek alphabet, used for the last carbon of the chainGreek o mega, great o
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Terms that go with it
- Fatty acidA fatty acid is a long chain of carbon and hydrogen atoms with a carboxyl group at one end, and is the building block of fats, oils and phospholipids.
- LipidA lipid is one of a varied group of biological molecules, including fats, oils, phospholipids, waxes and steroids, that do not dissolve in water.
- TriglycerideA triglyceride is a fat molecule made of one glycerol joined to three fatty acids, and it is the main form in which the body stores energy.
- CholesterolCholesterol is a waxy steroid lipid found in animal cell membranes and used to make steroid hormones, vitamin D and the bile salts that digest fat.
- PhospholipidA phospholipid is a lipid with two fatty acid tails and a head containing phosphate, and it is the main building block of all cell membranes.
- Cell membraneThe cell membrane is the thin, flexible boundary of lipids and proteins that encloses every cell and controls what enters and leaves it.
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Checked against
Written for biofideX in plain words, after checking these references:
- NCCIH: Omega-3 Supplements, What You Need To Know
- Harvard T.H. Chan School of Public Health, The Nutrition Source: Omega-3 Fatty Acids, An Essential Contribution
- NCBI MeSH: Fatty Acids, Omega-3
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